It has been proposed to design and construct busses, mobile homes, campers and the like out of prefabricated modular sections either composed of metal frame members or lightweight plastic sections which can be interconnected by means, such as, welding or bolts into a unitary body. Customarily, these sections are united with a chassis or base frame which carries the necessary motive power source and ground-engaging wheels. Construction of housings in modular sections greatly reduces manufacturing and assembly costs and at the same time can result in a lightweight but high strength housing comparable to those which have been made in the past out of heavier metals. Representative of this approach is European Reference No. 10969/L/LU, dated 6 December, 1985, to C-P Rohr et al. In Rohr et al, the approach taken is to construct modular frames making up longitudinal segments of the roof, sidewalls, floor and chassis section, and to interconnect such modular frames in end-to-end relation and with front and rear end sections closing off opposite ends of the assembled frame. The walls of the individual modular frames are composed of inner and outer plastic shells filled with a foam core material and are equipped with the necessary supply lines and ducts for operation of the conveyance as a bus or other suitable commercial transportation vehicle. However, the modular frame construction as described presupposes that the bus is of uniform cross-section throughout and, for example, does not make provision for mounting of an air conditioning system substantially within the roof line of the housing.
Other patents of interest pertaining to roof-mounted air conditioning systems for motor vehicles and specifically of a low-profile variety for buses are those to Krug et al U.S. Pat. No. 4,201,064, Hammers et al U.S. Pat. No. No. 2,032,572 and Schjolin U.S. Pat. No. 2,784,568. However, none is directed to a prefabricated bus and specifically with a modular roof section for use in combination with a low-profile modular air conditioning unit; and further wherein modular sections can be united with a conventional chassis into a lightweight but high strength structure.